1. Field of the Invention
The present invention relates generally to a method for fabricating a semiconductor device, and more particularly to a method for fabricating a semiconductor device that can reduce coupling noise between metal wiring that may result from higher degrees of device integration.
2. Description of the Background Art
As semiconductor devices become more highly integrated, the size of the semiconductor device becomes reduced. Also, as the size of a semiconductor device is reduced, the dimensions and interval between adjacent metal wiring leads, which are voltage feeding sources, are essentially shortened.
However, since a pair of neighboring metal wiring leads and an insulating interlayer interposed between the neighboring metal wiring leads operate together as a capacitor, parasitic capacitance increases if the interval between the metal wiring leads is shortened. Therefore, the coupling noise and interference between the adjacent metal wiring leads increases, so that RC-delay of the metal wiring leads and crosstalk between the metal wirings leads may occur.
In practice, since a DRAM includes a lower layer metal wiring leads and an upper layer metal wiring leads, which are twisted with each other while forming a resulting shape, and the combined metal wiring leads have long lengths, signal distortion may occur due to an increase in the parasitic capacitance. Accordingly, desirable device characteristics are affected negatively.
Accordingly, in order to reduce the coupling noise between the metal wiring leads that occurs in highly integrated devices, that is, in order to prevent the parasitic capacitance from increasing, low dielectric constant materials, having a dielectric constant lower than the dielectric constant (typically ∈=3.5˜4.4) of a silicon oxide layer (SiO2), has been currently developed for an insulating interlayer.
However, since a material to be replaced with the silicon oxide layer is only under development work without being currently commercially available, problems of RC-delay and crosstalk, resulting from the coupling noise between metal wiring leads, are not easily solved. Therefore, desirable device characteristics are not ensured.